``As dictators go, Mussolini was very humane .'' So writes Hoyt ( Japan's War ), who here presents an idiosyncratic interpretation of ``the world's most popular political figure of the late 1920s and early 1930s.'' Playing down the violence, corruption and anti-Semitism of Mussolini's regime--and the hammy theatricality of the man himself--Hoyt emphasizes the uneasy relationship between the Italian dictator and Hitler, especially Mussolini's restraining influence on der Fuhrer until 1939. Hoyt brings into focus, for example, Il Duce 's attempts to forge an alliance among Britain, France, Italy and Germany in 1933-1934 to maintain peace in Europe and curb the Nazi leader's expansionist ambitions. The author also sheds light on the Salo Republic, the puppet regime Hitler established in northern Italy for Mussolini after his fall from popular power in 1943 (Mussolini was executed by partisans in 1945). There is also a chapter on Mussolini's relations with women (``Usually he did not take off his trousers'') which, Hoyt acknowledges, has little relevance to his 21-year leadership of Italy or his contributions as a statesman. (Mar.)